If you, as a concealed carrier, see a person openly carrying an AR-15 into a theatre, do you leave? Or do you yell, HIP, HIP, HURRAY for the RKBA.

You can't just shoot him on sight. That could prove to be murder. You just thought you shot the next Aurora Movie Shooter, when you shot somebody going to theme party or some such. You can't shoot somebody for what they might do. If he's threatening people with with it? Shooting people? By all means! Move and shoot!

Likewise, a LEO can not make you eat pavement (or worse- as in the case of Erik Scott in Las Vegas 2 years ago) just because you have a gun on your hip (or in your IWB holster). Or should not be able to, as it does happen. When there is video of it, there can be negative consequences, and thus there would be less of that.

__________________
TheGolden Rule of Tool Use: "If you don't know what you are doing, DON'T."